Microbial Communities of Ascocarps and Soils in a Natural Habitat of Tuber Indicum

Abstract Truffles are the fruiting bodies of hypogeous fungi in the genus Tuber. Some truffle species usually grow in an area devoid of vegetation, called brûlé, which knowledge about the microbial composition and structure is still limited. Here, we investigated the bacterial and fungal communities of Tuber indicum ascocarps and soils inside and outside a characteristic brûlé from a poplar plantation with no truffle production history in northeastern China using a high-throughput sequencing approach. A predominance of bacterial phylum Proteobacteria was observed in all samples, with Bacillus among the main genera in the ascocarps, while members of Lysobacter and unidentified Acidobacteria were more abundant in the soil. In addition, Gibberella, Fusarium and Absidia were the dominant fungi in the ascocarps, while Tuber were enriched in the ascocarps and soils inside the brûlé. Soil samples from inside the brûlé had a lower bacterial diversity and a greater fungal diversity than did those from outside the brûlé. Furthermore, some mycorrhization helper bacteria (Rhizobium) and ectomycorrhiza-associated bacteria (Lysobacter) were detected, indicating their potential roles in the complex development of underground fruiting bodies and brûlé formation. These findings may contribute to the protection and cultivation of truffles.